#include<cstdio>//uncle-lu

int main()
{
	int n, temp = 1;
	double sum = 0;
	scanf("%d",&n);

	for(int i=1;i<=n;++i)
	{
		sum = sum + temp * 1.0/i;
		temp = temp * -1;
	}

	printf("%.4lf",sum);
}
